This invention relates to a composite blade assembly for use in turbomachinery, and particularly to an interface between a ceramic airfoil and a metal platform.
Current practice relating to ceramic blade configurations requires integral platform sections that are incorporated at the base of the airfoil during the manufacturing process. This adds cost to the component due to material, labor and machining costs that are associated with the fabrication of the integrated platform system. In fact, these are rather large costs in the overall cost distribution of the part manufacture.
Other composite blades include separately-formed airfoils and platforms, attached by mechanical means on the rotor. Still other composite blades use chemical joints between their metal platforms and ceramic airfoil sections. These arrangements are also labor-intensive and costly to manufacture.
Making the platform out of a metal material is extremely advantageous for lower temperature applications where the platform is not subjected to the highest temperatures.
Accordingly, there remains a need for a simple and relatively inexpensive ceramic blade configuration that can take advantage of ceramic airfoil technology but in combination with a metal platform which is desirable in some applications.